Tape cartridge improved boss door

ABSTRACT

The tape cartridge improved boss door provides a sleeve between the lower boss for the torsion spring to rotate around to decrease the stress applied to the top coil of the torsion spring. An improved catch contacts the top leg of the torsion spring at a point distant from the torsion spring coils to further reduce the force applied to the torsion spring and the frictional drag as the torsion spring rotates around the sleeve, thus decreasing the failure rate of the tape cartridge due to premature failure of the torsion spring.

FIELD OF THE INVENTION

This application is a 371 of PCT/US01/42585 Oct. 9, 2001

The invention relates to digital tape cartridges, and in particular, toan improved boss door for a single reel tape cartridge.

PROBLEM

It is a problem in the field of tape cartridges with door assembliesthat utilize boss components and a torsion spring to prevent tapecartridge failure caused by exerting undue stress on the torsion springwhile also providing a method for automatically pivoting the doorassembly open and closed when the tape cartridge is inserted into orremoved from the tape drive.

Single reel tape cartridges have a pivoting door that pivots open whenthe tape cartridge is inserted into the tape drive to expose theenclosed magnetic tape media for operation. The existing single reeltape cartridge boss door assembly is best described reading thefollowing description in conjunction with the prior art illustrated inFIGS. 1 and 2.

Torsion Spring Rotation—FIG. 1:

Referring to FIG. 1, the prior art boss door 130 assembly utilizes acylindrical post 110 integral to tape cartridge 100 and extending fromcover 102 to base 104 of tape cartridge 100 and an upper boss 132 and alower boss 134 integral to door 130. The upper and lower bosses 132 and134 include a cylindrical-shaped hole formed therein to fit over thecylindrical post. When assembled, upper and lower boss, 132 and 134respectively, rotate on cylindrical post 110. Lower boss 134 ispositioned on door 130 to create an area between lower boss 134 and base104 of tape cartridge housing 100 for torsion spring 120 to rotatearound cylindrical post 110. The inside diameter of torsion spring 120is significantly less than the outside diameter of the cylindrical post110 allowing torsion spring 120 to freely move from side to side and torotate around cylindrical post 110. Torsion spring 120 has a straighttop leg 122 and a straight bottom leg 124 that extend perpendicular adistance from torsion spring 120 coils. Top leg 122 is located adjacentto the base of lower boss 134 and bottom leg 124 is located at base 104of tape cartridge 100 housing and is retained against tape cartridge 100side wall 106.

A first problem with the prior art boss door 130 is that as the bossdoor 130 pivots, the diameter of the top coil of torsion spring 120decreases causing the top coil to rub against cylindrical post 110. Therubbing creates a frictional drag that keeps the top coil of the torsionspring 120 from rotating freely around cylindrical post 110 whichsubsequently increases the stress applied to top leg 122 of torsionspring 120. This stress is compounded by the distance between torsionspring 120 and cylindrical post 110 which allows torsion spring 120 toshift closer to one side of cylindrical post 110 than the other side.The increased stress on top leg 122 of torsion spring 120 may result intape cartridge failure due to premature failure of torsion spring 120.

Rectangular Catch—FIG. 2:

Referring to FIG. 2, boss door 130 also includes a rectangular catch 136projecting from boss door 130 below the bottom boss. Catch 136 is arectangular projection having right angle corners. When door 130 is inthe closed position, the force applied by top leg 122 of torsion spring120 to rectangular catch 136 holds door 130 closed. When the tapecartridge 100 is inserted into the tape drive, rectangular catch 136applies a force on top leg 122 pushing top leg 122 toward lower leg 124until boss door 130 is fully open. As tape cartridge 100 is removed fromthe tape drive, the force holding door 130 open is relieved and top leg122 of torsion spring 120 exerts a force on rectangular catch 136,pivoting door 130 to a closed position.

A second problem with the prior art boss door occurs when rectangularcatch 136 contacts with top leg 122 of torsion spring 120 at a pointproximal to the coils. Referring to FIG. 2, the end of the rectangularcatch 136 rotates in close proximity to torsion spring 120 coils andtherefore interfaces with top leg 122 of torsion spring 120 proximatethe coils. Contact at this point on top leg 122 of torsion spring 120generates additional tension on the top coil of torsion spring 120, thusincreasing the frictional drag as torsion spring 120 rotates aroundcylindrical post 110.

This problem is exacerbated by the construction of rectangular catch136. Rectangular catch 136 has a sharp corner where rectangular catch136 interfaces with top leg 122 of torsion spring 120. As boss door 130pivots against top leg 122 of tension spring 120, only the sharp edge ofrectangular catch 136 and a corresponding section of torsion spring 120top leg 122 make contact. Contacting top leg 122 or torsion spring 120at only one point that is distal from the coils increases the forcerequired to rotate the boss door 130 which places an increased stress ontorsion spring 120.

The boss door just described exerts unnecessary stress on the torsionspring resulting in failure of the tape cartridge due to prematuretorsion spring failure. For these reasons, a need exists for an improvedboss door that reduces the stress placed on the torsion spring toeliminate unnecessary tape cartridge failure.

SOLUTION

The present tape cartridge improved boss door provides an improvementthat reduces the stress exerted on the torsion spring, thus decreasingthe frictional drag as the torsion spring rotates around the cylindricalpost. The improved boss door also reduces the force required to pivotthe boss door open by relieving the tension on the torsion spring, thusreducing the failure rate of the tape cartridge due to premature failureof the torsion spring.

Torsion Spring Rotation:

The improved boss door provides a sleeve extending from the lower bossto the base of the tape cartridge. The outside diameter of the sleeve isslightly less than the inside diameter of the torsion spring and thetorsion spring rotates around the sleeve. The sleeve fills the gapbetween the cylindrical post and the torsion spring to prevent thetorsion spring from shifting closer to one side of the post than theother side, thus decreasing the stress applied to the top coil of thetorsion spring. Providing a sleeve extending from the lower boss makesthe improved boss door assembly compatible with existing tape cartridgehousings utilizing a boss door while reducing the force required torotate the improved boss door open.

Triangular Catch:

The improved boss door also replaces the rectangular catch with animproved catch that contacts a distal point on the torsion spring topleg. The improved catch is a triangular member that protrudes from theboss door. The sides of the triangular member do not interface with thetop leg of the torsion spring. Instead, only one corner of thetriangular member comes into contact with the top leg of the torsionspring. The point of contact is a point on the top leg distal from thetorsion spring top coil. Contact with the torsion spring top leg at apoint distal from the coils relieves the tension on the top coil as theboss door pivots open, thus reducing the frictional drag as the torsionspring rotates around the sleeve. The reduction in frictional dragdecreases the force required to open the door.

A sleeve to fill the gap between the torsion spring and the cylindricalpost provides an improved boss door that reduces the stress applied tothe torsion spring, thus decreasing the failure rate of the tapecartridge due to premature failure of the torsion spring. Providing animproved catch that contacts the torsion spring top leg at a pointdistal from the coils further reduces the stress applied to the torsionspring. Improving the mechanical characteristics to the door assemblywithout requiring improvements to the existing tape cartridge housingallows the improved boss door to be attached to existing tape cartridgehousings, thus reducing the cost to manufacture tape cartridges withimproved boss doors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of the prior art boss door;

FIG. 2 is a top view of the prior art boss door;

FIG. 3 illustrates a perspective view of the tape cartridge with a crosssectional view of the improved boss door; and

FIG. 4 is a top view of the improved boss door.

DETAILED DESCRIPTION

The tape cartridge improved boss door summarized above and defined bythe enumerated claims may be better understood by referring to thefollowing detailed description, which should be read in conjunction withthe accompanying drawings. This detailed description of the preferredembodiment is not intended to limit the enumerated claims, but to serveas a particular example thereof. In addition, the phraseology andterminology employed herein is for the purpose of description, and notof limitation.

The present tape cartridge improved boss door for single reel tapecartridges provides a sleeve attached to the lower boss that reduces thestress exerted on the torsion spring, thus decreasing the frictionaldrag as the torsion spring rotates around the sleeve. The improved bossdoor also reduces the force required to pivot the boss door open byrelieving the tension on the torsion spring created by the rectangularcatch by replacing the rectangular catch with a triangular catch.

As previously described in the prior art, boss door 230 assemblyutilizes a cylindrical post 210 integral to tape cartridge 100 andextending from cover 202 to base 204 of tape cartridge 200 and an upperboss 232 and a lower boss 234 integral to door 230. The upper and lowerbosses 232 and 234 include a cylindrical-shaped hole formed therein tofit over cylindrical post 210. When assembled, upper and lower boss, 132and 134 respectively, rotate on cylindrical post 110. Upper boss 232 hasnot changed, however, lower boss 234 has been improved.

Lower Boss with Sleeve—FIG. 3:

Referring to FIG. 3, lower boss 234 includes a sleeve 236 that projectsperpendicularly downward from lower boss 234 approximately to base 204of tape cartridge 200. The outside diameter of sleeve 236 is less thanthe inside diameter of torsion spring 220. When assembled, torsionspring 220 rotates around sleeve 236 as boss door 230 pivots. Top leg222 of torsion spring 220 extends outward from the top coil of torsionspring 220 adjacent lower boss 234. Bottom leg 224 of torsion spring 220extends outward from the bottom coil of torsion spring 220 along base204 of tape cartridge 200 housing. When the improved boss door 230pivots, bottom leg 224 of torsion spring 220 is held securely againstside wall 206 of tape cartridge 200 housing as top leg 222 of torsionspring 220 rotates toward bottom leg 224 of torsion spring 220.

Sleeve 236 eliminates the gap between the cylindrical post 210 andtorsion spring 220 as was found in the prior art tape cartridge bossdoor assemblies. Reducing the gap prevents torsion spring 220 fromshifting to one side or the other of sleeve 236 as boss door 230 rotatesaround cylindrical post 210, thus reducing the tension placed on torsionspring 220 during operation.

Providing sleeve 236 integrally formed to lower boss 234 does notrequire the tape cartridge 200 housing to be modified to operate withthe improved boss door 230. Instead, the improved boss door can beattached to existing tape cartridges to decrease the failure rate of thetape cartridges. An improved catch integrally formed to the improvedboss door further reduces the tension placed on the torsion spring.

Triangular Catch—FIG. 4:

Referring to FIG. 4, improved boss door 230 provides a triangular catch240 integrally formed to the back surface of improved boss door 230directly below lower boss 234. Triangular catch 240 projects from theback surface such that one corner of triangular catch 240 makes contactwith top leg 222 of torsion spring 220. The point of contact is a pointon top leg 222 distal from the top coil of torsion spring 220. Thetriangular catch 240 maintains the point of contact as boss door 230pivots between and open and a closed position.

Contacting top leg 222 of torsion spring 220 at a point distal from thetop coil decreases the force required to pivot boss door 230 open.Improving boss door 230 by replacing the rectangular catch withtriangular catch 240 combined with providing sleeve 236 for torsionspring 220 to rotate overcomes the problem of placing undue stress ontorsion spring 220 which generated a frictional drag as boss door 230rotated open.

Operational Characteristics—FIGS. 3 and 4:

Referring to FIG. 3, with boss door 230 closed, bottom leg 224 oftorsion spring 220 rests against side wall 206 of tape cartridge 200housing and top leg 222 of torsion spring 220 rests against the cornerof triangular catch 240 to hold improved boss door 230 closed. Referringto FIG. 4, as improved boss door 230 rotates toward an open position,triangular catch 240 places a force on top leg 222 causing the coil oftorsion spring 220 to begin to tighten against sleeve 236. Placing theforce at a point on torsion spring 220 top leg 222 distal from torsionspring 220 top coil reduces the force required to pivot improved bossdoor 230, thus reducing the stress placed on torsion spring 220.

Providing sleeve 236 for torsion spring 220 to rotate around preventstorsion spring 220 from shifting to one side or the other, overcomingthe problem of torsion spring 220 rubbing against cylindrical post 210.Preventing the rubbing reduces or eliminates the frictional drag thatkept torsion spring 220 from rotating freely around the cylindrical post210 in the prior art. Reducing or eliminating the frictional dragfurther decreases the force required to pivot boss door 230 open, thusfurther reducing the stress placed on torsion spring 220 top leg 222.

The improved boss door has been illustrated and described withimprovements to the lower boss and the catch located on the back surfaceof the boss door. Improving the boss door while maintaining the existingcharacteristics of the tape cartridge housing provides an improved bossdoor that is compatible with existing tape cartridge housings.Eliminating the need to manufacture a new tape cartridge housing toutilize the improved boss door reduces the cost to manufacture a tapecartridge utilizing the improved boss door to reduce tape cartridgefailure due to premature torsion spring failure.

In an embodiment of the tape cartridge improved boss door (notillustrated), a sleeve is integrally formed to the post and the torsionspring rotates around the sleeve. As previously discussed, thetriangular catch integral to the improved boss door makes contact withthe top leg of the torsion spring at a point distal from the tensionspring coils. While the embodiment just described is not compatible withexisting tape cartridge housing, an improved tape cartridge having asleeve integrally formed to the tape cartridge reduces the stressapplied to the torsion spring. Combining the improved tape cartridgehousing with an improved boss door having the improved catch furtherreduces the tension applied to the torsion spring to prevent prematurefailure of the tape cartridge due to torsion spring failure.

As to alternative embodiments, those skilled in the art will appreciatethat the present tape cartridge improved boss door can be configuredwith improvements to the boss door and the tape cartridge housing. Whilethe lower boss sleeve improvement can be incorporated by modifying thetape cartridge post, it would be necessary to manufacture a new tapecartridge housing as well as a boss door with the improved catch toreduce premature failure of the torsion spring.

It is apparent that there has been described, a tape cartridge improvedboss door that fully satisfies the objects, aims, and advantages setforth above. While the door assembly has been described in conjunctionwith specific embodiments thereof, it is evident that many alternatives,modifications, and/or variations can be devised by those skilled in theart in light of the foregoing description. Accordingly, this descriptionis intended to embrace all such alternatives, modifications andvariations as fall within the spirit and scope of the appended claims.

1. An improved door for a tape cartridge having a housing, the housingcomprising a cover, base, a post extending between the cover and thebase, a door having an upper and a lower boss, the upper and lower bosshaving a cylindrical-shaped hole formed therein to fit over the post,the upper and lower boss rotating on the post, and a torsion springlocated between the lower boss and the tape cartridge housing base, thetorsion spring having a plurality of coils, a top leg and a bottom leg,the improved door comprising: a sleeve integral to and extendingdownward from the lower boss to the base, wherein the torsion springrotates around the sleeve to reduce stress applied to the torsion springas the door rotates to an open position.
 2. The improved door of claim1, further comprising: a catch to make contact with the torsion springtop leg, wherein the catch contacts the top leg distal from theplurality of coils to reduce the force required to pivot the door openand to reduce the stress applied to the torsion spring.
 3. An improveddoor for a tape cartridge having a housing that encloses a single reelon which is wound a length of tape media, the housing having a cover, abase and a post integral to the housing, a door having an upper and alower boss wherein the upper and lower boss rotate around the post asthe door pivots between an open and a closed position, and a torsionspring located between the lower boss and the base of the tape cartridgehousing, the torsion spring having a plurality of coils, a top leg and abottom leg, the improved door comprising: a sleeve integral to the lowerboss, the sleeve extending downward between the lower boss and the base,an improved catch integral to the door to make contact with the torsionspring top leg, wherein the improved catch contacts the top leg distalfrom the plurality of coils and as the improved catch applies a force tothe top leg, the torsion spring rotates around the sleeve reducing thestress applied to the plurality of coils as the door rotates open.